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/*
*  RainFilter.cpp
*
*  Created by Daisuke Nogami on Nov, 05.
*  opyright 2005 Daisuke Nogami [null-null.net]. Some rights reserved.
*/
 
#include "stdafx.h"
#include "RainFilter.h"
 
 
#include "math.h"
#include "time.h"
 
 
////////////////////////////////////////////////////
// RainDrop
////////////////////////////////////////////////////
 
// param
#define GRAVITY 9.80619920
#define DAMPING 0.85
 
RainDrop::RainDrop(){
  init();
}
 
void RainDrop::init(){
  xpos = (float)rand()/RAND_MAX*1024;
  ypos = 768;
  velx = 10-(float)rand()/RAND_MAX*20;
  vely = -1*((float)rand()/RAND_MAX*30+30);
}
 
void RainDrop::move(){
  // move
  velx = DAMPING * velx;
  vely = DAMPING * ( vely - GRAVITY );
  xpos += velx;
  ypos += vely;
 
  // rebound
  if( ypos < 0 || ypos > 768 ){
    init();
  }
  else if( xpos < 0 ){
    xpos = 1024;
  }
  else if( xpos > 1024 ){
    xpos = 0;
  }
}
 
////////////////////////////////////////////////////
// RainFilter
////////////////////////////////////////////////////
 
// rain source power
#define MULT_RAIN_NUM 5
#define HIT_RANGE 30
#define RAIN_SRC_POW_A 1.0
#define RAIN_SRC_POW_B 0.8
 
void RainFilter::sync( float prec_rate ){
  raindrops.clear();
 
  int i;
  int rnum = prec_rate*MULT_RAIN_NUM;
  for( i = 0; i < rnum; i++ ){
    raindrops.push_back( RainDrop() );
  }
}
 
void RainFilter::update(){
  int i;
  RainDrop* rd;
  for( i = 0; i < raindrops.size(); i++ ){
    rd = &raindrops[i];
    rd->move();
  }
}
 
void RainFilter::mappingTo( CellSet* cellset ){
  int x, y, i, idx;
  float lenx, leny, len, nx, ny;
  Cell* tcell;
  RainDrop* rd;
 
  for( i = 0; i < raindrops.size(); i++ ){
 
    rd = &raindrops[i];
 
    for( y = 0; y < cellset->hdiv; y++ ){
      for( x = 0; x < cellset->wdiv; x++ ){
 
        idx = x+y*cellset->wdiv;
 
        // cell A
        tcell = &cellset->cells_a[idx];
        lenx = (tcell->xpos + cellset->xpos) - rd->xpos;
        leny = (tcell->ypos + cellset->ypos) - rd->ypos;
        len = sqrt( lenx*lenx+leny*leny );
        // hit test
        if( len < HIT_RANGE ){
 
          // effect from airstream
          nx = tcell->nextx;
          ny = tcell->nexty;
          rd->velx += nx*0.03; // x axis
          rd->vely += ny*0.03; // y axis
 
          tcell->add( rd->velx*RAIN_SRC_POW_A, rd->vely*RAIN_SRC_POW_A );
        }
 
        // cell B
        tcell = &cellset->cells_b[idx];
        lenx = (tcell->xpos + cellset->xpos) - rd->xpos;
        leny = (tcell->ypos + cellset->ypos) - rd->ypos;
        len = sqrt( lenx*lenx+leny*leny );
        // hit test
        if( len < HIT_RANGE ){
 
          // effect from airstream
          nx = tcell->nextx;
          ny = tcell->nexty;
          rd->velx += nx*0.03; // x axis
          rd->vely += ny*0.03; // y axis
 
          tcell->add( rd->velx*RAIN_SRC_POW_B, rd->vely*RAIN_SRC_POW_B );
        }
      }
    }
  }
}